Power tool with ergonomic handgrip

ABSTRACT

A power tool with an ergonomic handgrip includes a housing, a motor in the housing, a working end coupled to a front end of the housing, a handle extending distally from the housing, and a trigger coupled to the handle. The housing defines a tool axis, the handle defines a handle axis, and the trigger defines a trigger axis in its direction of movement. A first gripping region includes a rear concave recess on a rear end of the housing and a lateral concave recess along a lateral sidewall of the housing parallel to the tool axis. A vertical line extending from an innermost point of the rear concave recess intersects the trigger axis forward of where the trigger axis intersects the handle axis. A second gripping region includes a convex surface on a rear portion of the handle with an elliptical curvature having an eccentricity less than 0.5.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to and is a continuation-in-part ofU.S. Design Pat. Application No. 29/471,134, filed Oct. 29, 2013, titled“Screwdriver and Nosepiece,” which is incorporated herein by reference.

TECHNICAL FIELD

This application relates to a power tool, such as a drywall screwdriver,with an ergonomic handgrip.

BACKGROUND

Various drywall screwdrivers with handgrips are known in the art. Forexample, Applicant is aware of a Bosch 18-Volt Brushless DrywallScrewdriver (Model No. SG182BN), a Hilti Cordless Drywall Screwdriver(Model No. SD 4500-A18), and a Makita 18V LXT® Lithium-Ion CordlessDrywall Screwdriver (Model No. LXSF01Z). However, the handgrips of theseknown screwdrivers are lacking in ergonomic design, resulting in userdiscomfort and fatigue when the tool is used over a period of time.

SUMMARY

In an aspect, a power tool with an ergonomic handgrip includes a housingwith a rear end portion, a front end portion, and lateral sidewalls, anddefining a tool axis. A motor is disposed in the housing. A working endis coupled to the front end portion of the housing, and configured to bedriven by the motor. A handle has a proximal portion coupled to thehousing, a distal end portion away from the housing, a rear wallportion, and a front wall portion, and defines a handle axis. A triggeris coupled to the handle and defines a trigger axis extending in adirection of trigger movement. A first gripping region includes a rearconcave recess on the rear end portion of the housing and a lateralconcave recess extending along one of the lateral sidewalls of thehousing generally parallel to the tool axis. The rear concave recess hasan innermost point that is closest to the front end portion of thehousing. A second gripping region includes a convex surface on the rearwall portion of the proximal portion of the handle. A vertical lineextending from the innermost point generally perpendicular to the toolaxis intersects the trigger axis at a first intersection point that isforward of a second intersection point where the trigger axis intersectsthe handle axis.

Implementations of this aspect may include one or more of the followingfeatures. A third gripping region may be disposed on the housing, andoffset rearward of the front end portion of the housing. The triggeraxis may be generally perpendicular to the handle axis. The trigger axismay be at an acute angle of at least 15 degrees to the tool axis. Theconvex surface may have a curvature defined by an ellipse that has aneccentricity of less than 0.5. The ellipse may have a center proximateto the trigger axis. The ellipse may have a minor axis generallyparallel to the tool axis and a major axis generally perpendicular tothe tool axis. The convex surface may have a rearmost point that isapproximately 26 mm to 32 mm rearward of the innermost point andapproximately 70 mm to 80 mm distal of the innermost point. A fourthgripping surface may be on the rear wall portion of the distal portionof the handle extending along the handle to a point distal of thetrigger. The ergonomic handgrip may be configured to be grasped in oneof: (a) a first grip position where the first gripping region receives athumb and a forefinger of a user, the second gripping region receives ina palm of the user, and the trigger receives at least one of a ringfinger and a pinky finger of the user; and (b) a second grip positionwhere the second gripping portion receives the thumb of the user, thetrigger receives at least one of the forefinger and the middle finger ofthe user, and the fourth gripping region receives the palm of the user.

In another aspect, a power tool with an ergonomic handgrip includes ahousing with a rear end portion, a front end portion, and lateralsidewalls, and defines a tool axis. A motor is disposed in the housing.A working end is coupled to the front end portion of the housing, andconfigured to be driven by the motor. A handle has a proximal portioncoupled to the housing, a distal end portion away from the housing, arear wall portion, and a front wall portion, and defines a handle axis.A trigger is coupled to the handle and defines a trigger axis extendingin a direction of trigger movement. A first gripping region includes arear concave recess on the rear end portion of the housing and a lateralconcave recess extending along one of the lateral sidewalls of thehousing generally parallel to the tool axis. A second gripping regionincludes a convex surface on the rear wall portion of the proximalportion of the handle. The convex surface has a curvature defined by anellipse that with an eccentricity of less than 0.5.

Implementations of this aspect may include one or more of the followingfeatures. The trigger axis may be generally perpendicular to the handleaxis. The trigger axis may be at an acute angle of at least 15 degreesto the tool axis. The ellipse may have a center proximate to the triggeraxis. The ellipse may have a minor axis generally parallel to the toolaxis and a major axis generally perpendicular to the tool axis. The rearconcave recess may have an innermost point that is closest to the frontend portion of the housing, and the convex surface may have a rearmostpoint that is approximately 26 mm to 32 mm rearward of the innermostpoint and approximately 70 mm to 80 mm distal of the innermost point. Afourth gripping surface may be on the rear wall portion of the distalportion of the handle extending along the handle to a point distal ofthe trigger. The ergonomic handgrip may be configured to be grasped inone of: (a) a first grip position where the first gripping regionreceives a thumb and a forefinger of a user, the second gripping regionreceives in a palm of the user, and the trigger receives a ring fingerof the user; and (b) a second grip position where the second grippingportion receives the thumb of the user, the trigger receives theforefinger of the user, and the fourth gripping region receives the palmof the user.

In another aspect, a power tool with an ergonomic handgrip includes ahousing with a rear end portion, a first front end portion, a secondfront end portion, and lateral sidewalls, and defines a tool axis. Amotor is disposed in the housing. A working end is coupled to the frontend portion of the housing, and configured to be driven by the motor. Ahandle includes a proximal portion is coupled to the housing, a distalend portion away from the housing, a rear wall portion, a front wallportion, and a pair of sidewalls, and defines a handle axis. A triggeris coupled to the handle and defines a trigger axis extending in adirection of trigger movement. A first gripping region includes a rearconcave recess on the rear end portion of the housing and a lateralconcave recess extending along one of the lateral sidewalls of thehousing generally parallel to the tool axis. A second gripping regionincludes a convex surface on the rear wall portion of the proximalportion of the handle. A third gripping region is on the second frontend portion of the housing and is offset rearward from first front endportion. A fourth gripping region is on the rear end portion of thedistal portion of the handle. A fifth gripping region is on the frontwall portion of the distal portion of handle adjacent the trigger. Asixth gripping region is on the front wall portion of the distal portionof the handle, distal of the fifth gripping region. The handle has afirst depth from the trigger to the convex gripping surface, a seconddepth from the fifth gripping region to the fourth gripping region, anda third depth from the sixth gripping region to the fourth grippingregion, the first depth being greater than the second depth, and thesecond depth being greater than the third depth. The handle has a firstwidth between the sidewalls at the trigger, a second width between thesidewalls at the fifth gripping region, and a third width between thesidewalls at the sixth gripping region, the first width being less thanthe second width, and the second width being approximately equal to thethird width.

Implementations of this aspect may include one or more of the followingfeatures. The gripping regions may be configured to be grasped in oneof: (a) a first grip position where the lateral concave recessesreceives a thumb and a forefinger of a user, the rear concave recessreceives a web between the thumb and the forefinger of the user, theconvex gripping surface is received in a palm of the user, the thirdgripping region receives a middle finger of the user, and the triggerreceives at least one of a ring finger and a pinky finger of the user;and (b) a second grip position where the fourth gripping region receivesthe palm of the user, the convex gripping surface receives the web andthe thumb of the user, the fifth gripping region receives the ringfinger of the user, the sixth gripping region receives the pinky fingerof the user, and the trigger receives at least one of the forefinger andthe middle finger of the user. A trigger lock-on switch may be on thefifth gripping region.

Advantages may include one or more of the following. First, the positionof the innermost point of the first gripping region relative to thetrigger axis and the handle axis results allows the web between theuser's thumb and forefinger to lie closer to the trigger, resulting in amore ergonomic grip and easier actuation of the trigger. Second, theposition and low eccentricity of the ellipse defining the secondgripping region, and the position of the rearmost point of the secondgripping region allow the second gripping region to fill the palm of auser's hand without significant gaps, without creating pressure pointsin the palm, and without forcing the palm upward or rearward to push thefingers out of alignment with the tool axis and the trigger, resultingin a more ergonomic grip. Third, the angle of the trigger axis relativeto the tool axis and the handle axis, and the position of the lock-onswitch below the trigger allow for more ergonomic actuation of thetrigger and the lock-on switch. Fourth, the depth and width of thehandle at the trigger, at the fifth gripping surface, and at sixthgripping surfaces result in a more ergonomic grip when the tool is beinggripped in the second position. These and other advantages and featureswill be apparent from the description, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exemplary embodiment of ascrewdriver.

FIG. 2 is a left side view of the screwdriver of FIG. 1 with a portionof the exterior housing removed.

FIGS. 3A and 3B are left side views of the screwdriver of FIG. 1.

FIG. 4 is a close-up view of the trigger on the screwdriver of FIG. 1.

FIG. 5 is a front view of the screwdriver of FIG. 1.

FIG. 6 is a rear view of the screwdriver of FIG. 1.

FIG. 7 is a schematic illustration of the anatomy of a user's hand.

FIG. 8 is a right side view of the screwdriver of FIG. 1 being grippedin a first position.

FIG. 9 is a left side view of the screwdriver of FIG. 1 being gripped inthe first position.

FIG. 10 is a right side view of the screwdriver of FIG. 1 being grippedin a second position.

FIG. 11 is a left side view of the screwdriver of FIG. 1 being grippedin the second position.

FIG. 12 is a close up left-side view of the screwdriver of FIG. 1.

DETAILED DESCRIPTION

Referring to FIGS. 1 and 2, in one embodiment, a power tool 10 has ahousing 12 having a front end portion 18, a rear end portion 22, andsidewalls and defining a tool axis X-X. The housing 12 includes a motorhousing portion 13 that contains a rotary motor 14 and a transmissionhousing portion 15 that contains a parallel axis transmission 20 thattransmits rotary motion from the motor 14 to an output spindle 26.Coupled to the front end portion 18 of the transmission housing portion15 and mechanically connected to the output spindle 26 is a working endor tool holder 16 for retaining a tool bit (e.g., a drill bit or screwdriving bit, not shown) and defining a tool holder axis X-X. As shown,the tool holder 16 includes a hex bit retention mechanism. Furtherdetails regarding exemplary tool holders are set forth in commonly-ownedU.S. patent application Ser. Nos. 12/394,426 and 14/186,088, which areincorporated herein by reference. The working end 16 could encompassother elements, such as a different hex bit holder, a chuck, a nosepieceof a nailer or stapler, or a saw blade holder. The motor 14 drives theworking end or tool holder 16 via the transmission 20 and the outputspindle 26. A nosepiece or magazine may optionally be coupled to thefront end portion 18 of the housing 12, as described and shown in theaforementioned U.S. patent application Ser. No. 14/186,088, which isincorporated by reference.

Extending downward and slightly rearward of the housing 12 is a handle40 in a pistol grip formation. The handle 40 has a proximal portion 42coupled to the housing 12 and a distal portion 44 coupled to a batteryreceptacle 28. The handle 40 also has a first front wall portion 43 anda second front wall portion 59 facing the tool holder 16 side of thetool, a rear wall portion 41 facing away from the tool holder 16 side ofthe tool, and sidewalls 49. The handle 40 extends generally along ahandle axis Y-Y that is at an obtuse angle α to the tool bit holder axisX-X and that lies along a midline of the handle 40. For example, theangle α may be approximately 100-115 degrees, e.g., approximately 106degrees, such that the distal portion 44 is located generally rearwardand downward of the rear end portion 22 of the housing 12. It should beunderstood that this angle can be varied among a wide range of angles.

The motor 14 may be powered by an electrical power source, e.g., abattery (not shown), which is coupled to the battery receptacle 28. Atrigger 30 is coupled to the handle 40 adjacent the motor housingportion 13 of the housing 12. The trigger 30 electrically connects thebattery (or other source of power) to the motor 14 via an electronicswitch and control module 29 for controlling power delivery to the motor14. The trigger 30 defines a trigger axis Z-Z extending along thedirection of trigger travel, which is generally perpendicular to thehandle axis Y-Y. A light unit (e.g., an LED) 27 may be disposed on thebattery receptacle 28 and may be angled to illuminate an area in frontof the tool holder 16. Power delivery to the light unit 27 may becontrolled by the trigger 30 and the electronic switch and controlmodule 29, or by a separate switch on the tool. As shown in thedrawings, the power tool is a battery powered cordless screwdriver.However, it should be understood that the tool may be any type ofcorded, cordless, pneumatic, or combustion powered tool, such as adrill, an impact driver, a wrench, a hammer, a hammer drill, a nailer, astapler, a saw, a grinder, a sander, or a router.

Referring to FIG. 3A, the power tool 10 includes an ergonomic handgrip50 designed to be contoured to a user's hand. The ergonomic handgrip 50includes a first gripping region 52 on the transmission housing portion15, a second gripping region 54 on the rear wall portion 41 of theproximal portion 42 of the handle 40, a third gripping region 53 on themotor housing portion 13, a fourth gripping region 56 on the rear wallportion 41 of the distal portion 44 of the handle 40, a fifth grippingregion 45 on a front wall portion 43 of the proximal portion 46 of thehandle 40 adjacent to the trigger 30, and a sixth gripping region 47 onthe front wall portion 43 of the proximal portion 46 of the handle 40distal of the fifth gripping region 45 and adjacent the batteryreceptacle 28. One or more of the gripping regions 52, 53, 54, 56, 45,47 may be formed or covered with an elastomeric material, such as rubberor a resilient plastic material, and may include one or more ridges orrecesses to facilitate gripping of these regions.

Referring also to FIGS. 3B-6 and 12, the first gripping region 52 has apair of longitudinal concave recesses 56 extending generally along orparallel to the tool axis X-X on opposite sidewalls 58 of thetransmission housing portion 15. The longitudinal concave recesses 56extend along most of the length of the transmission housing portion 15,and include ridges 61 to enhance gripping of the recesses 56. The firstgripping region 52 also has a rear concave recess 60 in communicationwith the longitudinal concave recesses 56 and wrapping around the rearend portion 22 of the housing 12. The rear concave recess 60 has aconcave curvature having a radius of curvature R1 of approximately 10 mmto 15 mm (e.g., approximately 13.5 mm). When viewed from the side asshown in FIG. 3B, the rear concave recess 60 has an innermost point 64that is closest to the first front end portion 18 of the housing 12. Theinnermost point 64 generally coincides with or is proximate to the toolaxis X-X. The first gripping region 52 has a first height H1 ofapproximately 25 mm to 35 mm (e.g., approximately 27 mm).

The second gripping region 54 includes a generally convex grippingsurface 65 that wraps around the rear wall portion 41 of the proximalportion 42 of the handle 40 and covers at least a portion of thesidewalls 49 of the handle 40. As shown in FIG. 12, the convex grippingsurface 65 has a curvature that is generally defined by an ellipse 66centered at a center point 68 that is proximate the trigger axis Z-Z andthat is positioned below and in front of the trigger 30. The ellipse 66has a minor or horizontal axis 72 that is generally parallel to the toolaxis X-X and a major or vertical axis 70 that is generally transverse tothe tool axis X-X. The major axis 70 has a length “a” of approximately142 mm to 152 mm (e.g., approximately 152 mm), and the minor axis 72 hasa length “b” of approximately 135 mm to 145 mm e.g., approximately 140mm). In one embodiment, both the major axis 70 and the minor axis 72intersect at least a portion of the trigger 30. Although the centerpoint 68 is not shown as intersecting the trigger axis Z-Z, it should beunderstood that they may intersect. It should also be understood thatthe ellipse 66 may instead be a circle, or may have a major axis in thehorizontal direction or in a direction transverse to the vertical andhorizontal directions.

The ellipse 66 has a relatively small eccentricity. Eccentricity is ameasurement the amount that an elliptical shape surface deviates fromcircular, and is given by the following equation:

${{Eccentricity} = \sqrt{1 - \frac{b^{2}}{a^{2}}}},$

where a=½ the length of the major axis 70 and b=½ the length of theminor axis 72. Eccentricity is measured on a scale of 0 to 1, with 0being circular, and values approaching 1 being elongated in onedirection and flattened in the other direction, approaching a straightline. In the illustrated embodiment, the ellipse 66 that defines theconcave gripping surface has an eccentricity of is less than 0.5, suchas, for example, between approximately 0.3 and 0.4. In one possibleembodiment, the eccentricity of the ellipse may be approximately 0.38.

The second gripping region 54 has a second height H2 of approximately 50mm to 65 mm (e.g., approximately 58 mm). The second gripping region 54also has a rearmost point 57 at a point farthest rearward and distalfrom the innermost point 64. The rearmost point 57 is positioned adistal distance DD of approximately 70 mm to 80 mm (e.g., approximately71 mm) distally of the innermost point 65, and a rearward distance RD ofapproximately 26 mm to 32 mm (e.g., approximately 29 mm) rearward of theinnermost point 65. The rearmost point 57 is also generally proximate tothe rearward end of the minor or horizontal axis 70 of the ellipse 66.

The third gripping region 53 comprises a generally flat gripping surface59 that is disposed on the second front end portion 55 on the motorhousing portion 13 and that partially wraps around the sides of themotor housing portion 13. The third gripping region 53 has a height H3and is disposed a first offset distance L1 forward of the innermostpoint 64 of the concave recess 60 and a second offset distance L2 fromthe front end portion of the longitudinal concave recess 56. The heightH3 may be approximately 25 mm to 35 mm (e.g., approximately 30 mm), thefirst offset distance L1 may be approximately 50 mm to 95 mm (e.g.,approximately 84 mm), and the second offset distance L2 may beapproximately 13 mm to 64 mm (e.g., approximately 27 mm).

The fourth gripping region 56 has a gripping surface 63 that wrapsaround the rear wall portion 41 of the distal portion 44 of the handle40 and covers at least a portion of the sidewalls 49 of the handle 40.When viewed from the side as in FIG. 3B, the gripping surface 63 issubstantially straight with a slight convex curvature. The fourthgripping region 56 has a height H4 of approximately 60 mm to 70 mm(e.g., approximately 65 mm).

The fifth gripping region 45 comprises a generally flat front restingsurface 80 formed on the front wall portion 45 of the distal portion 44of the handle 40 adjacent the trigger 30, and side resting surfaces 82formed on the sidewalls 49 of the distal portion 44 of the handle 40.Disposed on the finger resting surface 80 is a lock-on switch 74 thatcan be actuated to lock-on the trigger 30 when it is depressed. Thefifth gripping region 45 a height H5 of approximately one finger width,e.g., approximately 20 mm to 30 mm (e.g., approximately 25 mm).

The sixth gripping region 47 comprises a generally convex finger restingsurface 84 that wraps around the front wall portion 45 of the distalportion 44 of the handle 40 and onto both sidewalls of the handle 40,distal of the fifth gripping region 45 and adjacent the batteryreceptacle 28. The convex finger resting surface 84 may be joined withthe side resting surfaces 82 as one continuous surface. The sixthgripping region 47 has a height H6 of approximately one finger width,e.g., approximately 20 mm to 30 mm (e.g., approximately 25 mm).

The trigger 30 generally has an L-shape with a generally straight frontsurface 33 and a generally straight top surface 35 joined by a curvedcorner surface 37. The front surface 33 has a height H7 of approximatelytwo finger widths, for example approximately 33 mm to 43 mm (e.g.,approximately 38 mm). The straight top surface 35 has a depth D ofapproximately 8 mm to 15 mm (e.g., approximately 11 mm). The curvedcorner surface 37 has a radius of curvature R2 of approximately 7 mm to13 mm (e.g., approximately 10 mm) defined by a circle 39 with a centerpoint C. The trigger axis Z-Z extends through the center point C in thedirection of trigger travel, generally perpendicular to the handle axisY-Y. The trigger axis Z-Z is at an acute angle β of at least 15 degrees,e.g., approximately 15 to 20 degrees (such as 17 degrees) to a line L-Lthat is parallel to the tool holder axis X-X.

The ergonomic grip 50 facilitates ergonomic gripping of the tool by auser's hand in two different grip positions during operation of thetool. FIG. 7 illustrates the anatomical parts of a user's handGenerally, a user's hand 100 includes a palm 101 to which is connected athumb 102, a forefinger 104, a middle finger 106, a ring finger 108, anda pinky finger 110. A web 112 of muscles connects the base of the thumb102 and forefinger 104. In addition, the palm 101 includes a centerregion 111 flanked by two fleshy pads in the form of a thenar eminence114 on the thumb side of the palm and the hypothenar eminence 116 on thepinky side of the palm. Further, there are fleshy pads 118, 120, 122,124, and 126 on the palm 101 at the base of the thumb 118 and eachfinger 104, 106, 108, and 110.

The handle 40 has a first depth D1 and a first width W1 at the trigger,a second depth D2 and a second width W2 at the fifth gripping region 45,and a third depth D3 and a third width W3 at the sixth gripping region47. The first, second, and third depths D1, D2, D3 are measured from thetrigger to the second gripping region 54, from the fifth gripping region45 to the fourth gripping region 56, and from the sixth gripping region47 to the fourth gripping region, respectively. The first depth D1 isgreater than the second depth D2, which is greater than the third depthD3. For example, the first depth D1 is approximately 45 mm to 55 mm(e.g., approximately 50 mm), the second depth D2 is approximately 40 mmto 45 mm (e.g., approximately 42 mm), and the third depth D3 isapproximately 35 mm to 40 mm (e.g., approximately 37 mm). The first,second and third widths W1, W2, W3 are measured between sidewalls 49 ofthe handle 40 at the trigger 30, at the fifth gripping region 45 and atthe sixth gripping region 47, respectively. The first width W1 is lessthan the second width W2, which is approximately equal to the thirdwidth W3. For example, the first width W1 is approximately 30 mm to 35mm (e.g., approximately 32 mm), the second width W2 is approximately 31mm to 36 mm (e.g., approximately 35 mm), and the third width W3 isapproximately 28 mm to 37 mm (e.g., approximately 35 mm).

Referring to FIGS. 8 and 9, when gripped in the first grip position, thelongitudinal concave recesses 56 of the concave gripping region 52receive the thumb 102 and forefinger 104, which are generally alignedalong the tool holder axis X-X. The rear concave recess 60 receives theweb 112 that connects the thumb 102 and forefinger 104. The secondgripping region 54 is received in the center region 111 of the palm 101with the thenar eminence 114 on one side of the second gripping region54 and the hypothenar eminence 116 on the other side of the secondgripping region 54. The middle finger 106 rests alongside the motorhousing portion 13 with the fingertip of the middle finger 106 restingon the third gripping region 53. The ring finger 108 and the pinkyfinger 110 rest on the trigger 30 and are used to actuate the trigger30. The pinky finger 110 can also be used to actuate the lock-on switch74.

Referring to FIGS. 10 and 11, when gripped in the second grip position,the fourth gripping region 56 receives the center region 111 of the palm100 with the thenar eminence 114 on one side of the fourth grippingregion 56 and the hypothenar eminence 116 on the other side of thefourth gripping region 56. The forefinger 104 and middle finger 106 arereceived on the trigger 30. The ring finger 108 is positioned to rest onthe front surface resting surface 80 and side resting surface 82 of thefifth gripping region 45. The pinky finger 110 is positioned to rest onthe finger resting surface 84 of the sixth gripping region 47. The web112 and thumb 102 rest on the second gripping surface 54. The trigger isactuated using the forefinger 104 and/or middle finger 106, while thelock-on switch 74 is actuated using the ring finger 108.

One or more of the following features, alone or together, proved thehandgrip 50 with superior ergonomics. First, the position of theinnermost point 64 of the first gripping region 52 results in a moreergonomic design. A vertical line V-V taken from the innermost point 64on the rear concave recess 60 intersects the trigger axis Z-Z at anintersection point 86 that is forward of the handle axis Y-Y. Thisconfiguration allows the web 112 between the thumb 102 and forefinger104 to lie in a plane that is closer to the trigger 30 when the handle40 is gripped in the first position. This allows the user's grip to becentered forward of the handle axis, resulting in a more ergonomic gripand easier actuation of the trigger.

Second, the configuration of second gripping region 54 results in a moreergonomic grip. Advantageously, the ellipse 66 that defines the secondgripping region 54 has a relatively low eccentricity of less than 0.5,such as 0.3 to 0.4, resulting in a curvature that is neither too shallownor too sharp. In addition, the rearmost point 57 of the second grippingregion 54 is positioned proximate the rear end point to the horizontalaxis 70 of the ellipse 66. The rearmost point 57 is positioned at adistance DD of approximately 70 mm to 80 mm (e.g., approximately 71 mm)distally of the innermost point 65, and a rearward distance RD ofapproximately 26 mm to 32 mm (e.g., approximately 29 mm) from theinnermost point 64 of the first gripping region 52. Further, the centerpoint 68 of the ellipse 66 is positioned just below and in front of thetrigger, and within the circle 39 that defines the radius R2 of thecurved trigger surface 37. These aspects of the second gripping region54 allow the second gripping region 54 to fill the palm of a user's handwithout significant gaps, without creating pressure points in the palm,and without forcing the palm upward or rearward to push the fingers outof alignment with the tool axis and the trigger.

Third, the configuration of the trigger 30 and lock-on switch 74 resultsin a more ergonomic grip. The trigger 30 travels along the trigger axisZ-Z, at an acute angle β of at least 15 degrees to the tool holder axisX-X (e.g., approximately 17-20 degrees). The trigger axis Z-Z is alsogenerally perpendicular to the handle axis Y-Y. This orientation of thetrigger axis Z-Z results in a more ergonomic and natural movement forthe ring finger and pinky finger to pull the trigger when the tool isbeing gripped in the first position, and for the forefinger and middlefinger to pull the trigger when the tool is being gripped in the secondposition. Further, the lock-on switch 74 is positioned on the fifthgripping region 45, just below the trigger 30. This allows the pinky toactuate the lock-on switch 74 when the tool is gripped in the firstposition and the ring finger to actuate the lock-on switch 74 when thetool is gripped in the second position.

Finally, the configuration of the fourth, fifth and sixth grippingsurfaces result in a more ergonomic grip when the tool is being grippedin the second position. The first depth D1 at the trigger is greaterthan a second depth D2 at the fifth gripping region 45, which is greaterthan the third depth D3 at the sixth gripping region 47. At the sametime, the first width W1 at the trigger 30 is smaller than the secondwidth W2 at the fifth gripping region 45, which is approximately equalto the third width W3 at the sixth gripping region 47. Having thesmallest width W1 and largest depth D1 at the trigger 30 allows thesides of the handle to comfortably receive the thenar eminence 114 andthe hypothenar eminence 116 while the forefinger and middle finger graspthe trigger. The larger widths W2 and W3 at the finger rests 43 and 45allow the handle to be comfortably received in the center of the palm.The larger depth D2 at the finger rest 43 than the depth D3 at thefinger rest 45 provides a more comfortable grip for the larger ringringer and smaller pinky finger.

Numerous modifications may be made to the exemplary implementationsdescribed above. For example, the trigger may be moved upward andrearward on the housing so that it is closer to the tool axis and to thehandle axis. Also, the housing may have only one portion with the motorbeing in-line with the transmission or directly driving the working endwithout a transmission. These and other implementations are within thescope of the following claims.

What is claimed is:
 1. A power tool with an ergonomic handgripcomprising: a housing with a rear end portion, a front end portion, andlateral sidewalls, the housing defining a tool axis; a motor disposed inthe housing; a working end coupled to the front end portion of thehousing, and configured to be driven by the motor; a handle with aproximal portion coupled to the housing, a distal end portion away fromthe housing, a rear wall portion, and a front wall portion, the handledefining a handle axis; a trigger coupled to the handle, the triggerdefining a trigger axis extending in a direction of trigger movement; afirst gripping region including a rear concave recess on the rear endportion of the housing and a lateral concave recess extending along oneof the lateral sidewalls of the housing generally parallel to the toolaxis, the rear concave recess having an innermost point that is closestto the front end portion of the housing; and a second gripping regionincluding a convex surface on the rear wall portion of the proximalportion of the handle, wherein a vertical line extending from theinnermost point generally perpendicular to the tool axis intersects thetrigger axis at a first intersection point that is forward of a secondintersection point where the trigger axis intersects the handle axis. 2.The power tool of claim 1, further comprising a third gripping regiondisposed on the housing, and offset rearward of the front end portion ofthe housing.
 3. The power tool of claim 1, wherein the trigger axis isgenerally perpendicular to the handle axis.
 4. The power tool of claim1, wherein the trigger axis is at an acute angle of at least 15 degreesto the tool axis.
 5. The power tool of claim 1, wherein the convexsurface has a curvature defined by an ellipse that has an eccentricityof less than 0.5.
 6. The power tool of claim 5, wherein the ellipse hasa center proximate to the trigger axis.
 7. The power tool of claim 5,wherein the ellipse has a minor axis generally parallel to the tool axisand a major axis generally perpendicular to the tool axis.
 8. The powertool of claim 1, wherein the convex surface has a rearmost point that isapproximately 26 mm to 32 mm rearward of the innermost point andapproximately 70 mm to 80 mm distal of the innermost point.
 9. The powertool of claim 1, further comprising a fourth gripping surface on therear wall portion of the distal portion of the handle extending alongthe handle to a point distal of the trigger.
 10. The power tool of claim9, wherein the ergonomic handgrip is configured to be grasped in one of:(a) a first grip position where the first gripping region receives athumb and a forefinger of a user, the second gripping region receives ina palm of the user, and the trigger receives at least one of a ringfinger and a pinky finger of the user; and (b) a second grip positionwhere the second gripping portion receives the thumb of the user, thetrigger receives at least one of the forefinger and the middle finger ofthe user, and the fourth gripping region receives the palm of the user.11. A power tool with an ergonomic handgrip comprising: a housing with arear end portion, a front end portion, and lateral sidewalls, thehousing defining a tool axis; a motor disposed in the housing; a workingend coupled to the front end portion of the housing, and configured tobe driven by the motor; a handle with a proximal portion coupled to thehousing, a distal end portion away from the housing, a rear wallportion, and a front wall portion, the handle defining a handle axis; atrigger coupled to the handle, the trigger defining a trigger axisextending in a direction of trigger movement; a first gripping regionincluding a rear concave recess on the rear end portion of the housingand a lateral concave recess extending along one of the lateralsidewalls of the housing generally parallel to the tool axis; and asecond gripping region including a convex surface on the rear wallportion of the proximal portion of the handle, wherein the convexsurface has a curvature defined by an ellipse that with an eccentricityof less than 0.5.
 12. The power tool of claim 11, wherein the triggeraxis is generally perpendicular to the handle axis.
 13. The power toolof claim 11, wherein the trigger axis is at an acute angle of at least15 degrees to the tool axis.
 14. The power tool of claim 11, wherein theellipse has a center proximate to the trigger axis.
 15. The power toolof claim 11, wherein the ellipse has a minor axis generally parallel tothe tool axis and a major axis generally perpendicular to the tool axis.16. The power tool of claim 1, wherein the rear concave recess has aninnermost point that is closest to the front end portion of the housing,and the convex surface has a rearmost point that is approximately 26 mmto 32 mm rearward of the innermost point and approximately 70 mm to 80mm distal of the innermost point.
 17. The power tool of claim 11,further comprising a fourth gripping surface on the rear wall portion ofthe distal portion of the handle extending along the handle to a pointdistal of the trigger.
 18. The power tool of claim 17, wherein theergonomic handgrip is configured to be grasped in one of: (a) a firstgrip position where the first gripping region receives a thumb and aforefinger of a user, the second gripping region receives in a palm ofthe user, and the trigger receives a ring finger of the user; and (b) asecond grip position where the second gripping portion receives thethumb of the user, the trigger receives the forefinger of the user, andthe fourth gripping region receives the palm of the user.
 19. A powertool with an ergonomic handgrip comprising: a housing with a rear endportion, a first front end portion, a second front end portion, andlateral sidewalls, the housing defining a tool axis; a motor disposed inthe housing; a working end coupled to the front end portion of thehousing, and configured to be driven by the motor; a handle with aproximal portion coupled to the housing, a distal end portion away fromthe housing, a rear wall portion, a front wall portion, and a pair ofsidewalls, the handle defining a handle axis; a trigger coupled to thehandle, the trigger defining a trigger axis extending in a direction oftrigger movement; a first gripping region including a rear concaverecess on the rear end portion of the housing and a lateral concaverecess extending along one of the lateral sidewalls of the housinggenerally parallel to the tool axis; a second gripping region includinga convex surface on the rear wall portion of the proximal portion of thehandle; a third gripping region on the second front end portion of thehousing and offset rearward from first front end portion; a fourthgripping region on the rear end portion of the distal portion of thehandle; a fifth gripping region on the front wall portion of the distalportion of handle adjacent the trigger; and a sixth gripping region onthe front wall portion of the distal portion of the handle, distal ofthe fifth gripping region, wherein the handle has a first depth from thetrigger to the convex gripping surface, a second depth from the fifthgripping region to the fourth gripping region, and a third depth fromthe sixth gripping region to the fourth gripping region, the first depthbeing greater than the second depth, and the second depth being greaterthan the third depth, and wherein the handle has a first width betweenthe sidewalls at the trigger, a second width between the sidewalls atthe fifth gripping region, and a third width between the sidewalls atthe sixth gripping region, the first width being less than the secondwidth, and the second width being approximately equal to the thirdwidth.
 20. The power tool of claim 19, wherein the gripping regions areconfigured to be grasped in one of: (a) a first grip position where thelateral concave recesses receives a thumb and a forefinger of a user,the rear concave recess receives a web between the thumb and theforefinger of the user, the convex gripping surface is received in apalm of the user, the third gripping region receives a middle finger ofthe user, and the trigger receives at least one of a ring finger and apinky finger of the user; and (b) a second grip position where thefourth gripping region receives the palm of the user, the convexgripping surface receives the web and the thumb of the user, the fifthgripping region receives the ring finger of the user, the sixth grippingregion receives the pinky finger of the user, and the trigger receivesat least one of the forefinger and the middle finger of the user. 21.The power tool of claim 20, further comprising a trigger lock-on switchon the fifth gripping region.